article 38 nonhuman 32 Animals 24 Male 24 Rats 22 animal cell 22 controlled study 22 unclassified drug 22 Female 20 animal experiment 18 female 18 hydroxyprogesterone 18 priority journal 18 rat 18 Hydroxyprogesterones 14 male 14 Humans 12 Progesterone 12 radioisotope 12 steroid 12 11alpha hydroxyprogesterone 10 Animal 10 Thymus Gland 10 drug structure 10 enzyme activity 10 human 10 in vitro study 10 11beta hydroxypregna 1,4 diene 3,20 dione 8 11beta hydroxyprogesterone 8 17-alpha-Hydroxyprogesterone 8